The present invention is directed to the asymmetric epoxidation of allylic alcohols.
U.S. Pat. No. 4,471,130 teaches to epoxidize allylic alcohols using titanium complexes containing optically active alkoxide ligands as catalyst in the presence of an alkyl hydroperoxide oxidate. This catalyst system always delivers the epoxide oxygen from the same enantioface of the olefin regardless of the substitution pattern. Thus, the use of L(+)-dialkyl tartrate leads to the formation of the (S)-glycidol, whereas the use of D(-)-dialkyl tartrate leads to the (R)-glycidol. Although this reaction provides a simple synthetic route to the desired epoxy alcohol enantiomers, the disadvantage of the method of the patent is that the D(-)-dialkyl tartrate is much more expensive than the natural L(+)-dialkyl tartrate.